We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
Long Distance Amateur Work in
Australia
By F. BASIL COOKE, F. R. A. S.
In Australia, as here, the tendency in amateur transmitting is toward reduction in the power accompanied by increase in the distance covered. In this account of an Australian amateur's station there are several features which may well be taken advantage of by Americans. Operating power tubes below their rated filament voltage, for instance, is a practice not usually found in this country. Transmitting 450 miles on 3.8 watts is quite an achievement, and we find that our confreres in Australia are using such highly developed receiving arrangements as the "reflex" circuit. We should like to hear more from Australia. — THE EDITOR.
MR. CHARLES MACLURCAN of Strathfield, near Sydney, has been devoting his energies with remarkable results to low-power transmission, throughout all his tests never exceeding 9 watts. He has designed every unit of his apparatus to contribute to a maximum efficiency to allow him to transmit farther than other experimenters have been able to do with the same power.
In order that his results may be fully appreciated, the writer wishes to give here a brief description of his station. A glance at the accompanying diagram shows that the circuit employed is a well-known one and reveals that the modulation is brought about by direct grid control. This method has been practically abandoned by many experimenters in favor of the valve system of modulation. It is therefore of interest to know that Mr.
Maclurcan has demonstrated that, for low power, this simple and inexpensive means of producing voice currents is at least as efficient as the elaborate and expensive valve system.
The transmitting valves are Radiotron 5-watt power tubes of which three are employed. The filament is supplied with only 6 volts instead of 7.5 in order that the tubes may have a longer life. The plate current exciting the tubes is drawn from a generator, developing 300 volts and passing 30 milli-amperes, giving a maximum input current of 9 watts.
The aerial and earthing systems deserve special mention. The aerial consists of four i8-gauge copper wires equally spaced round wooden hoops z\ feet in diameter. The hoops are placed 15 feet apart. The two spans are each 100 feet. The centre is fixed to an 80foot mast while the two ends are supported by 25-foot masts. The feeder (lead-in) con
MR. MACLURCAN'S TRANSMITTER